Inverted rectifier



F. W. MEYER.

INVERTED RECTIFIER.

APPLICATION FILED JUNE 20,1914.

1,381,324. I Pat nted June 14, 1921.

3 SHEETS-SHEET l.

0 Q I I l l I O l I I C v WITNESSES: Km W35 INVENTOR I M 7/ I; fH'edr/M W/Veye/ F. W. MEYER.

INVERTED RECTIFIER.

APPLICATION FILED JUNE 20, 1914.

1,381,324 Patented June 14,1921.

3 SHEETS-SHEET 2.

m p? 3000 RPM. v M 7- 3 4' 3/ 3600 RPM.

WITNESSES: INVENTOR F. W. MEYER.

INVERTED RECTIFIER.

APPLICATION FILED JUNE 20. 1914.

1,381,324. Patnted June 14,1921.

3 SHEETS'TSHEET 3.

PATENT OFFICE.

FRIEDRICH W. MEYER, OF PITTSBURGH,

PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA.

INVERTED RECTIFIER.

Specification of Letters Patent.

Patented June 14, 1921.

Application filed June 20, 1914. Serial No. 846,365.

T 0 all whom it may concern:

Be it known that I, FRIEDRICH W. MEYER, a subject of the Emperor of Germany, and a resident of Pittsburgh, in the count of Allegheny and State of Pennsylvania, liave invented a new and useful Improvement in Inverted Rectifiers, of which the following is a specification.

My invention relates to. devices for transforming direct current into alternating current, and more particularly to devices of the character specified wherein the current is carried at the point of transition by means of a gas or vapor arc.

The object of my invention is to provide a device of the character specified which will be simple and effective in operation, which will have few moving mechanical parts, and which will require a minimum of attention.

It has previously been suggested in the United States patent to Kruh, No. 787,192, April 11, 1905, and Steinmetz, No. 787,228, April 11, 1905, to make use of the property of a vapor arc to seek a cool anode to provide apparatus for converting direct current into alternating current. The devices of these two patents depend entirely for their action upon this thermo effect, which is uncertain and erratic in its action, and which is afiected to a marked extent when the entire device heats up with use and as the room temperature changes. Furthermore, changes in the load, with consequent changes in the strength and heating effect of the arcs, alter the frequency and operation of these devices to a marked extent. While they work successfully under ideal conditions in the laboratory, they are not susceptible of general commercial use beause of these defects. It has furthermore been proposed to transform direct current into alternating current by means of a magnetically controlled vapor arc, in United States patent to Weintraub, No. 877,026. January 21, 1908. The device of this patent operates by alternately blowing out or eX- tinguishing the arc and has been found defective for the following reason. The only electrode material which has been found suitable for power-carrying arcs of this character, is mercury or compounds thereof or hydrogen or helium when using a Wehnelt cathode. The current-carrying particles in a mercury vapor are are of considerable mass and hence possessed of considerable inertia, and when it is attempted to reverse the direction of movement of an arc of this character, at a reasonably high rate, such, for example, as that which is attendant upon commercial frequencies, an unnecessarily large number of ampere turns must be employed to provide a very powerful controlling field before effective operation is assured. It is a well-known fact that much less energy is required to move a heavy mass alternately from one point to another by causing it to revolve in a circular path which includes both of said points, rather than in causing it to reciprocate, because the sudden stoppage of a moving mass is invariably attended by a'loss of energy. I avail myself of this phenomenon to provide a de-rectifying device somewhat similar to that of Weintraub, but in which the arc-bearing material, possessing considerable inherent mass, is forced to travel in a circular path and hence smooth operation is assured. 7

Not only may energy in the form of an electromagnetic field be employed for controlling the arc, but I have found that energy in the form of. an electrostatic field also furnishes a very effective control, and I make use of either of these methods of control 'or of a system wherein both are combined.

Referring to the accompanying figures, Figure 1 is a side view, partially in section and partially in elevation, of a multi-current, multi-frequency inverted rectifier constructed in accordance with my invention. Fig. 2 is a bottom view, in plan, of the device shown in Fig. 1. Figs. 3 and 4 are perspective views illustrating the de-rectifying action of an arc in the device of Figs. 1 and '2. Fig. 5 is a side view, partially in section and partially in elevation, of an inverted rectifier, wherein the arc is actuated in a circular manner by means of a combined electrostatic and electromagnetic field, the tubes of force of each field being parallel to those of the other. Fig. 6 is a top plan view of the device of Fig. 5. Fig. 7 is a bottom plan view thereof. Fig. 8 1s a plan view of a modification of the device shown in Figs. 1 and 2. Fig. 9 is a side view, in section, of the device shown in Fig.

7 rise to a field, wherein all'the tu s tating ener 8, and Fig 10' shows a of rd field wherein both -electro- Figs. 1, an 2, '14 is a highlyexhausted con- -'taining receptacle of any suitable impervious material, such, for example,: as glass or' metal. When'constructed of metal,-so n'1e non-magnetic, non-amalgamating substance, such, for example,'as nickel-iron alloy should be employed." A cathode 15 of mercury or other suitable reconstructin vapor emitting substance,.is located the ower 'portion of" the container 14. Two upwardly extending flanges} 16 and 17 are formed inthe wall of the'con'tainer, and are so disposed that the}: are radial, throu hout' their length, wit

respect to the cat ode 15. A plurality of elongated anodes 18 and 19 are mounted in these flanges sothat there is a stralght free 'arc path between each of them and the cathode 15. A plurality of electromagnetsf .20 and'21 are mounted to embrace the anodes 18 and 19 and are connected to a rotating. commutating device connected to a main source, of direct current 23. The commutating device 22 is provided with one insulating segment 24 so that as it is rotated, each ofthe magnets 20 is, in turn,',deenergized for one-sixth of arevolution. The ma nets 20, all 'havelike polesfacihg outward y so that a field similar tothat employed in some tiypes of unipolar generators is provided.

he-magnets 21 are excited in a simllar manner (not shown); The magnets 20 and 21 'may be mounted on the outside of the container as shown, or they may be mounted inside thereof, if desired. In the latter case,

- oxid or.enamel insulated wire should be employed in order that the evacuation of the container ,may be carried to the proper point.

Having thus described the structure of the device of Figs. 1 and 2, the operation is as follows: Assumin an arc to bestarted between one of the ano es 18 andthe cathode 15 in any suitable and well known manner, the magnets 20 are energized and saidv are at once takes up a position between-the pole pieces of the magnet 20 WhlChlS deenergized because oftheinsulatingsegment24. Aseach of the magnets is 'deenergized in succession with the rotation of the commutatin device 22, the upper end of the arc moves orward accordingly so as. to always remain between the poles of the deenergized magnetand the arc, as a whole, generates, by its movement a conical surface whose apex is in the cathode 15. Therefore, the rate of rotation of the arc maybe readily controlled by varying the in the prima .former 25' w 'ch induces-current in the to the form of device shown in alternating current the anodes is substantially 180 a sine curve as is customary.

rotates, itimpinges successively upon each of the. anodes l8 and causescurrent to .flow

windings7O of a trans secondary windings 71+-71j thereof, havin the general characteristics and pro 'erties o ich may three-phase alternating current w be taken off by the mains 26. If it is desired to alter the frequency of the alternating current in the mains 26,,the speed of the commutating device 22 is changed. I iise the above expression having the general characteristics and properties of three phase advisedly, for the reason that if relativel hor1 anodes be employed, each phase wil be energized for but one-third of the time, and each alternating current wave willhave a length of 60 el'ec- ,trical de ees, instead of 180 degrees, as is usual. f it is desired to obtain alternating current more nearly ap roximating ordinary alternating current in 1ts characteristics,-the

anodes 18 may be extended in length and certain of them displaced radially so that there is a general overlapping. If each of in length, and each of them has the same relative location as is now the case, a current will be ob- .tained which will be similar to .ordinary three-phase alternating current, the main difference being that the shape will be extremely flat-topped instead of approximating The rotating field set up b the magnets 21 may have an entirely di erent angular velocity from the rotating field set up by the magnets 20, and I find that no difliculty is experienced in operating two arcs within the same container, each of said 'arcs generating conical surfaces in its rotation and each of said arcs being entirely different in its angular velocity. In this manner, for example, both 25 cycle and 60 cycle alternating current may 'be obtained from the same container and from the same source of direct current. Furthermore, two separate sets of an'odesmay, if desired, be arranged so that one are impinges upon both of them simul taneously and generates alternating current for two separate circuits, which circuits will havediflerent frequencies ifthe number of anodes therefor are different; These actions are illustrated in 18l8 and 19-19 of thedevice of Fig. 1 are shown. in skeleton view, together with the cathode 15 and the transformer 25 associated with the anodes 1818 and a similar transformer 25 associated with the anodes 1919. An are 75 is shown operatin upon the anodes 18-18 and is rotated at, or example, 3600 revolutions per minute by the proper control of the associated magnetic rotating means, generating 60 cycle current in the transformer 25 as shown. In a like manner, an are 76 operating on the anodes 19-19 may be rotated. at a velocity of 1500 revolutions per minute, generating -25-cycle current in the transformer 25.

In the arrangement shown in Fig. 4, the two sets of anodes 18-18 and 19-19 are more closely associated with each other so that a single arc ma play upon. both sets. If the are be rotate at a velocity of 3600 revolutions per minute and if there be six anodes in the set 18-18 and four anodes in the set 19-19, as shown, 60-cycle current is generated in the transformer 25 associated with the anodes 1818 and 40-cycle current is generated in the transformer 25' associated with the anodes 19-49, By proper design of the container 14 and of the strength of the rotating magnetic field for the specific angular velocity of the arc which is desired, a condition of equilibrium may be obtained wherein the centrifugal force of the small current-carrying particle is sufiicient to maintain the are on the anodes 18 in opposition to the natural tendency of the arc to flow in a direction normal to the surface of the cathode 15.

In the form of my device shown in Figs. 5. 6 and T I have shown how an arc may be caused to rotate so as to generate a conical surface by a. suitable field having both electrostatic and electromagnetic components. An evacuated container 47 of any suitable material is provided with a plurality of anodes 48 in the upper portion thereof, said anodes being arranged to lie in a circular path as clearly shown in Fig. 6. A cathode 49, of mercury or other suitable material, occupies the lower portion of the container 47. An alternating current electromagnet 50, energized from suitable mains 51, is mounted within the container, and supported by suitable lugs 52. The electromagnet 50 is provided with two salient poles 53 which embrace the arc path. A pair of conducting plates 54 are mounted immediately in front of the pole pieces 53 and are connected, respectively, to the terminals of the secondary winding of a step-up transformer 55 connected to the supply means 51 through a suitable phase displacing device 56. When the mains 51 are energized, a rotating field of energy with respect to the vapor arc will be set up between the plates 54 because of the fact that for a brief interval of time, for example, one of the plates 54 will be positively charged and the other will be negatively charged, causing the arc to move toward the positively charged plate because of the combined action of attraction and repulsion from the two plates respectively. 90 electrical degrees later, the plates 54 will be at substantially the same potential and the electrostatic force therebetween will be substantially zero but the magnetic field between the pole pieces 53 will be at a maximum, owing to the phase displacing action of the device 56. Under the influence of the electromagnetic field a vapor arc would be forced in a given direction in. a plane parallel to the plates 54. At the end of the succeeding 90 electrical degrees, the arc would be drawn toward the other plate 54 because of the reversal of polarity and at the end of the next succeeding ninety electrical degrees the arc will be forced in an opposite direction in a plane parallel to the plates 54 because of the reversal of the magnetic flux. \Vhen, therefore, an arc is initiated between an anode 48 and the cathode 49 and the mains 51 are energized by alternating current, the arc will be caused to rotate so that its positive end engages all the anodes 48 in succession, a three phase current may be caused to be generated in the same manner as in the device shown in Figs. 1 and 2.

In the form of my device shown in Figs. 8 and 9, I have shown how it is not necessary that the are be forced to generate a conical surface in order that the same have a true circular motion but the said are may be caused to operate in substantially a single plane with very effective results. A highly exhausted container of any suitable material is provided with a plurality of anodes 57 and with a cathode 58. The container is placed in a rotating magnetic field generated by a suitably wound ring 59 of magnetic material surrounding the same and energized from a suitable source of alternating current such for example as the polyphase supply system 60. lVhen an arc is initiated between one of the anodes 57 and the cathodes 58 from any suitable source 61 and the main 60. are energized, the arc will be caused'to rotate so that its positive ends impinge upon each of the anodes 57 in succession and a substan tially plane surface is generated by the movement of the arc path. The conditions affecting rotation of the are are somewhat different than in the structure of Figs. 1 and 2. \Vith a rotating field of the character indicated, there will always be two diametrically opposite points where the flux is zero. The are would take up a position at either one of these points. It is accordingly necessary, in order to obtain as definite a control of frequency and of phase relation as is the case with the devices of Figs. 1 and 2, to employ pairs of anodes, located 180 degrees apart, in place of each of the anodes of Figs. 1 and 2. Thus to generate three-phase current, I employ twelve anodes 57, diametrically opposite ones being connected to the same current lead in each case. It will be observed that. with a device of this character, after the arc has once been started into rotation. the movement thereof is substantially independent of the mass of the arc particles. The action of centrifugal force In the'form of 10, I havedisclosed statically charged plates. alternating current electromagnet 63 energized from mains 64.- is provided with pole p1eces'65- f adapted to embrace the arc path. An insulating joint 66 is provided in the mag netic circuit so that the two pole pieces 65 are electrically separated fromeac'h other.

The terminals of t e secondary member of a suitable step-up transformer are connected I directly to the pole'pie'ces 65 and the trans- I former 67' is energized from. the mains -64 I so 6 and 7.

through a phase displacing device- 68. By this construction, the pole pieces 65 act alternately as electromagnetic and {as electros static poles and in such a manner'as 'to-gen-- crate a rotating field of-energy therebetween,

in all respects similar to that-generated be tween the plates54 in the device of.F1gs. 5,

With anyof the above described pieces of apparatus, I may,.if desired, especially when generating alternating current of high frequency, provide an arc whose. current carrying particles are ofrelatively small mass, employing such materials, for example, as

hydrogen or helium for the conducting material.

While I havein all cases shown but a single cathode, it is obvious that I may employ a plurality of cathodes distributed in a circu-- lar path and cause an are from one anode to flow thereto and to be rotated in such a manner as to generate a conical surface. Such a structure, however, would present the disadvantage that it would be necessary to separately maintain a negative electrode reluctance of each of the cathodes in a broken down condition by separate maintaining means whereas with the structures that I have shown, the cathode activity is maintained. Furthermore, it would be possible to construct a device wherein a plurality of anodes were arranged in a circular path and a plurality of cathodes were also arranged in a circular path and wherein the arc would be rotated in such a manner as to generate a cylindrical surface. Such a structure, however, would be somewhat unstable in its operation and I deem the structure shownin the figures to be somewhat more practicable.

Where it is desired to generate alternating currents of comparatively high voltage, with attendant liability to anode short circuits, it is generally advisable to operate the inverted rectifier at a moderate voltage and to subsequently modify the output by ordinary transformers, even though this occaaccount of the extra apgiratus an I, of the greaterv relative e segtrate electro-iand a plurality of electrodes arran engaged in succession byone on of said r iron-sat sions a diminution ofthe efiiciency both on because voltage drop in-the va or are.

Asanelectrostatic eld must necessarily be very narrow-in order to have a powerful controlling -action,-one may, if it is desired to oscillate an arc'through a considerable angle, employ a plurality "of parallel-connectcd electrostatic fields, arranged in tan- .dem. :These may be displaced wlth respect to each other along the arc path,

ect of the constant q if desired,

so that they 'will exert little influence on While I have shown various modifications; of my invention in the appended drawingi I do not wish tolbe restricted thereto but I sire that 1 only such restrictions be placed upon-my invention. as ares'et forth in the appended claim s.

I claim asm 'mve'ntlonz' I A.'d8V1C0 I or; converting direct current into pulsating producing a directrcurrent arc, means for causing said arc to revolveaabout an axis, ed to be ,into pulsating current comprising means for current comprising means producing a direct-current arc, and means for causing said unto rotate about an axis,

"one end of said are operating continuously froman electrode and the other end impinging in succession upon each of a plurality of electrodes.

3. The combination with an evacuated container, of a plurality of electrodes therein, certain of said electrodes being mounted to lie in different elements of an imaginary conical surface, an electrode at the apex ofsaid conical surface, means for maintaining a direct-current are between said last named electrode and the first named electrodes, and means for causing said arc to rotate so that it always lies in said conical surface.

4c. The combination with an evacuated container, of a plurality of electrodes mounted therein, certain of said electrodes being arranged substantially equidistant about the perimeter of a circle, an electrode mounted substantially" equidistant from all of said first named electrodes,.means for maintaining a direct-current are between saidlast named electrode and the first named electrodes, and means for causing said are to,rotate about an axis normal to the plane of said circle at substantially the central portion thereof, so that one end of said are will impinge upon each of said circularly disposed electrodes in succession.

5. The combination with means producing a rotating field of energy, of a Y plurality of electrodes, means for roducing an arc'within the influence of said field of energy, and

- the plurality of electrodes so disposedtliat,

as the arc is rotated by the field of energy, it connects a certain one of said electrodes in succession with each of the others.

'6. The combination with an evacuated container, of a plurality of electrodes therein, certain of said electrodes being mounted to lie in different elements of an imaginary conical surface, an electrode at the apex of said conical surface, means for maintaining a direct-current are between said last named electrode and the first named electrode, and means producing a rotating field of ener surrounding said container, whereby said are is caused to rotate so that it always lies substantially in said conical surface and impinges upon the electrodes mounted therein in succession.

7 Means-for producmg a rotat n field of energy comprismg means for pro uclng a continuously reversing electromagnetic field and means for producing a continuously reversing electrostatic field, said fields being of like frequency and disposed to act in space and time-quadrature to each other upon a predeterminedspace.

8. Means for producinga rotatin field of energy comprising means for pro ucing a continuously varying electromagnetic field and means for producing a continuously :varying electrostatic field, said fields vary-v ing at like rates'and'being disposed to act' I upon a common space with space displacement.-

9. Means for producing a rotating field of force comprising means for producing a varying electromagnetic field and means for producing a varying electrostatic field, the

mutual time and lines of force in said two fields coinciding in Y direction,-the magnetic field being at maxisaid two-fields coinciding indirection, themagnetic field being at maximum strength when the electrostatic field is at substantially minimum strength andvice versa. I

In testimony whereof, I have hereunto subscribed my name this, 19th day of June, 1.914;. v Q

' FRIEDRICH W. MEYER.-

' Witnesses:

D; 'C. DAVIS, B. B; Hrrms. 

